Did anything feel different when you were trying to start it?
Well, I do remember that the more I re-pulled the starter rope, the more numb I felt.
Until eventually, after what seemed like more than a hundred pulls . . . I apparently turned into a numbskull. ?
But no, everything felt and looked normal as ever. So I had no idea why it wasn't starting, as it had always typically started within a couple pulls. And I don't think I recalled that it had backfired - the last time I had shut it down, but perhaps it did. Maybe it doesn't take much of a backfire to blow a head gasket if the engines' usage hours are high, which was the case with ours; purchased it in 96' or 97', and I think the head gasket blew in 2014~15, so it was 18 or 19 yrs old.
Then after I had to replace the cylinder head, due to my—glad to say temporary—infliction of being a numbskull who torqued the head bolts to 200 ft-lbs—instead of the proper 200 in-lbs
—it started right back up and ran great.
In the meantime, we purchased a Husqvarna from Lowe's that had several non-starting issues, so after several mowing's promptly returned it to Lowe's and with our refund money bought a Honda mower from HomeDepot that's been super great; it's now 6 or 7 yrs old and still
starts every time on the 1st pull !=))